Design of a Screw Jack Mechanism to Avoid Self-excited Vibrations

Abstract

This paper deals with vibratory phenomena that are encountered in screw jack mechanisms, down-motion especially. One can find many practical instances where such mechanisms are subject to vibratory conditions. Besides producing loud noise, vibrations can easily damage the mechanism. Although the screw jack mechanism has been widely employed, its behavior is still not fully understood. In order to explain the vibration phenomenon, we propose a simple two D.o.F. dynamic model. Using this kind of model, it is shown that vibrations can be avoided by reducing the axial stiffness of the screw.